1. Field of the Invention
This invention relates to a binocular stereomicroscope for use as a microscope for surgical operations, or the like.
2. Description of the Prior Art
For example, when surgical operations are carried out on minute diseased parts, enlarged images of the diseased parts have heretofore been formed with binocular stereomicroscopes, and the diseased parts have heretofore been treated by seeing the enlarged images. Such a binocular stereomicroscope comprises an objective lens and a magnifying optical system, which substantially constitutes a binocular magnifier and which is located at the rear of the objective lens. In order to adjust the focusing point of the binocular stereomicroscope, a mechanism provided with a rack and pinion, which is formed on a stay and which vertically or horizontally moves the whole binocular stereomicroscope, has been put into practice.
Also, a binocular stereomicroscope has heretofore been known which is provided with an illumination means for illuminating an object. The illumination means is constituted such that a light beam for illumination, which has been produced by a light source, may pass through an objective lens and may then impinge upon the object.
However, the conventional binocular stereomicroscope described above is not provided with an automatic focusing function. Therefore, the operator of the binocular stereomicroscope must manually carry out a focusing operation while he views an enlarged image. Also, for example, when the binocular stereomicroscope is removed from the object during its use, visual treatment is carried out on the object, and then the binocular stereomicroscope is used again, an operation must be carried out to correct the focusing point, which has shifted accompanying the movement of the binocular stereomicroscope. The re-focusing operation is also required when the position of the object to be viewed is changed. Thus considerable time and labor are required to carry out the focusing operations.
In particular, in cases where the binocular stereomicroscope is used for a surgical operation and a state of emergency, e.g., bleeding, occurs during the surgical operation, the binocular stereomicroscope must be removed from the object, and an urgent treatment must be carried out on the object. When the surgical operation is again carried out on the object, it is necessary to carry out a re-focusing operation. Thus, movement and the focusing operation of the binocular stereomicroscope must be carried out in addition to the treatment on the diseased part. Therefore, there is the risk that the surgical operation cannot be carried out quickly.
In order to eliminate the problems described above, it is considered to utilize a mechanism provided with a special frame and a storage means such that, after a binocular stereomicroscope is removed from the position of observation, the binocular stereomicroscope can again be returned to the same focusing position with respect to the position of observation. However, in cases where the binocular stereomicroscope is provided with such a mechanism, a large-sized mechanism is required to adjust the position of the whole binocular stereomicroscope, which is heavy, in accordance with a predetermined focusing point. Therefore, the binocular stereomicroscope cannot be operated smoothly, and its cost cannot be kept low.